Wind power is considered one of the cleanest, most environmentally friendly energy sources presently available, and wind turbines have gained increased attention in this regard. A modern wind turbine typically includes a tower, generator, gearbox, nacelle, and one or more rotor blades. The rotor blades capture kinetic energy from wind using known airfoil principles and transmit the kinetic energy through rotational energy to turn a shaft coupling the rotor blades to a gearbox, or if a gearbox is not used, directly to the generator. The generator then converts the mechanical energy to electrical energy that may be deployed to a utility grid.
During operation of a wind turbine, each rotor blade is subject to deflection and/or twisting due to the aerodynamic wind loads acting on the blade, which results in reaction loads transmitted through the blade. To control these loads and to allow for a maximum amount of wind energy to be captured by the rotor blades, the blades are typically pitched during operation. Pitching generally involves rotating each rotor blade about its pitch axis in order to alter the orientation of the rotor blades relative to the wind, thereby adjusting the loading on each rotor blade.
In many instances, the operation of a wind turbine must be stopped due to system failures and/or other emergency events. For example, wind turbine stop events may include controller failures, pitch system failures, other component failures, grid loss, power failure, other emergency situations and/or the like. Currently, wind turbine control systems utilize a single, uniform stopping procedure in order to halt operation when a wind turbine stop event occurs. Specifically, conventional control systems are designed to pitch the rotor blades to the feather position at a single, predetermined pitch rate regardless of the wind turbine stop event. However, each stop event is typically characterized by unique design driven loads. For example, unlike other wind turbine stop events, the failure of one or two of the pitch systems of a wind turbine typically results in a substantial increase in the asymmetric or unbalanced loads acting on the wind turbine. Unfortunately, conventional stopping procedures are not capable of efficiently and effectively stopping the operation of a wind turbine when such increased asymmetric loads exist.
Accordingly, an improved system and/or method for stopping the operation of a wind turbine when a pitch system failure occurs would be welcomed in the technology.